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Advancing Cellular Backhaul Through SatelliteRichard Deasington, Director, Market Development, iDirect

The mobile industry is at an important cross-

roads. With new technology emerging every

day, mobile operators are rapidly moving from

GSM standard 2nd generation (2G) networks to

3rd generation (3G) and 4th generation (4G) net-

works. With these changes, however, come

challenges. While 2G networks offered primari-

ly voice connectivity, 3G and 4G networks are

much richer and more complex, offering Internet

access, video, and much more. As such, they

deliver a significantly greater volume of data.

In major urban areas, there is the infrastructure

to support all of this data, but in rural areas, it

is much harder for mobile operators to backhaul

3G and 4G data affordably. Fortunately, there is

a solution. Mobile operators that have used

advanced satellite technology to backhaul 2G

traffic are discovering that it is also a viable

solution for backhauling more complex and

bandwidth-heavy 3G and 4G voice and data.

This article will examine how satellite delivers

cellular backhaul for 3G and 4G, the ways that

satellite has evolved in the last several years to

be more efficient and affordable, and the impli-

cations that the expansion of 3G and 4G cellular

services has had on the Asia-Pacific region.

Advancing Cellular Backhaul Through SatelliteOver the past decade, mobile technology has

been advancing at a phenomenal rate and

nowhere have these changes been felt more

strongly than in the developing world where

mobile devices are the primary way that individ-

uals access the Internet. In a 2010 report, Cisco

projected that mobile data traffic would grow

from 14 million to 788 million users by 2015 - a

26-fold increase. With an ever-increasing num-

ber of subscribers transitioning from 2G mobile

phone networks to 3G and 4G technology, we’re

coming closer to that reality. For mobile opera-

tors, however, tapping into rural communities is

easier said than done.

A key challenge preventing mobile operators

from delivering 3G and 4G service to developing

regions, including many areas in Asia-Pacific, is

backhauling rural network traffic. Because

these regions are often remote and cut off from

terrestrial communications, it can be difficult for

mobile operators to backhaul cellular data

affordably. While this was less of a concern

with previous mobile technology, which was pri-

marily focused on voice communications, 3G

and 4G mobile provide voice, video, and Internet

FEATURESⅢFEATURESⅢ

18 Quarterly Newsletter Q2•2012 19

access, which accounts for significantly greater

data volume.

Fortunately, there is a solution for mobile opera-

tors, and it’s one that they’re already familiar

with: satellite. Mobile operators can look to sat-

ellite as a solution for growing 3G and 4G net-

works in rural areas in the same way that they

used it to grow 2G networks. Furthermore,

because of significant recent advances in satel-

lite technology, mobile operators can leverage

satellite solutions even more efficiently than

before.

To understand how mobile operators can use

satellite technology for 3G and 4G, it’s impor-

tant to revisit how satellite helped mobile oper-

ators manage 2G data. The legacy approach for

backhauling cellular data relied on a technology

called SCPC (Single Channel Per Carrier). This

technology extends an E1 (or T1) fractional link

from the Base Station Controller (BSC) site to

the Base Transceiver Station (BTS) using a pair

of devices called SCPC modems. This solution

was effective for sites that had a high level of

traffic, but was operationally inefficient for

more remote and rural locations.

Because the capacity of the satellite link

between two SCPC modems has to be configured

for peak usage – which typically occurs for only a

few hours on the busiest day of the year – it ends

up costing mobile operators significant money in

wasted bandwidth. The shift in the market that

enabled mobile operators to backhaul data via

satellite more efficiently came in the mid-2000s

with the deployment of IP technology instead of

TDM (Time Division Multiplex) links.

As cellular data began to become more complex,

IP networks offered more efficiency to operators

by providing the ability to share capacity

between multiple sites rather than having a

fixed amount per site, as in a TDM network.

Concurrent to this change in the mobile industry

was a shift to IP in the satellite industry.

IP-based satellite networks use a concept called

TDMA (Time Division Multiple Access) to share

bandwidth across many sites. Through TDMA

technology, it is possible to allocate satellite

bandwidth on demand, based on the real-time

requirements of each site. When you pool band-

width like this, it creates a significant “trunking

gain” – requiring up to 80% less capacity on a

per site basis.

Modern carrier-class satellite systems built for

IP traffic are highly compatible with newer

IP-based 2G, as well as IP-based 3G and emerg-

ing 4G networks. Additionally, there have been

several other key technical innovations in the

satellite industry that made backhaul over satel-

lite an especially compelling option for 2G and

continue to make it a viable solution for 3G and

4G mobile operators.

The first key innovation supporting backhaul

over satellite was the move to the second gen-

eration of the Digital Video Broadcasting stan-

dard, or DVB-S2. This transition has made

TDMA networks significantly faster, particularly

when fine-tuned for maximum efficiency. The

addition of Adaptive Coding and Modulation

(ACM) technology makes satellite even more

efficient.

ACM enables each remote to operate at its

most efficient coding and modulation scheme at

any moment, depending on its location within

the satellite contour, antenna size and atmo-

spheric conditions. In practical terms, ACM

ensures that satellite connectivity will be unin-

terrupted by sudden weather changes in regions

where rain fade was previously a problem and

allows the satellite links to be configured on the

basis of optimal operation under clear sky con-

ditions instead of having to assume worst-case

conditions.

A second important development was the inte-

gration of TDMA and SCPC technology onto a

single networking platform. This innovation,

pioneered by iDirect, allows mobile operators to

use an SCPC Return channel when they need to

sustain fairly constant capacity, or to switch to

a TDMA link when throughput is more variable.

This flexibility takes away the guess-work from

network deployment – having to predict which

sites will be high-traffic in advance of their roll-

out.

Combining TDMA and SCPC on one platform not

only saves bandwidth but also lowers up-front

capital expenses by eliminating the need to

implement different types of ground infrastruc-

ture. Rather than sending a team to physically

swap a remote modem, a mobile operator can

switch modes from a central NOC using the

same hardware in the field. This is a powerful

incentive for mobile operators, particularly in

the Asia-Pacific region where rural subscribers

may be in areas where geographies and topog-

raphies make deployment difficult.

A third key development in the mobile industry

that has made cellular backhaul over satellite

appealing is the introduction of small cell/femto-

cell technology. Mobile operators are already

familiar with small cells as a means of offload-

ing data from the wireless network to the terres-

trial network, but they also offer the ability to

cost-effectively expand a wireless service area.

Many vendors are offering small cell platforms,

power amplifiers, power supplies and outdoor

enclosures to produce packages that can sup-

port 30 – 60 voice calls plus HSPA data traffic

and backhaul that traffic using any available IP

connectivity – including carrier-class satellite.

Compared to macro-cell solutions, which have

to be mounted on high towers and are expen-

sive to deploy and maintain, the price of these

small cell packages are significantly lower and,

combined with a low-cost remote satellite rout-

er, allow mobile operators to expand coverage

into rural areas quickly and economically.

Small cell solutions are challenging the tradi-

tional models that were used by mobile vendors

by developing new systems that incorporate the

entire 3G core network on the same server plat-

form that hosts the small cells. The effect of

this is to release mobile operators from the

need to operate large and extremely expensive

proprietary 3G core networks and replace them

with much lower cost soft-switches. These

devices allow scaling to much smaller networks

– even to allow entirely separate networks to

be operated in a building, ship or aircraft.

Given the game-changing potential of femtocell

technology, mobile operators that are already

RNC TeleportHub System Remote Node B

IP interfaceIP interface

IP-Based Cellular Network

20 Quarterly Newsletter

invested in Femto-gateways for core operations

in major cities are naturally interested in lever-

aging their existing investment to support rural

coverage.

Mobile Data Statistics in AsiaOne important characteristic of satellite tech-

nology as it relates to cellular backhaul is that

satellite can be integrated easily with existing

terrestrial networks. When you consider mobile

data usage trends in Asia, it is easy to see how

this can be a valuable benefit.

According to research from the International

Telecommunication Union1, South Korea and

Japan are ranked number one and number two

worldwide in mobile broadband penetration,

with 91 and 87.8 percent penetration respec-

tively. The ITU also found that, by the end of

2011 there were 6 billion mobile subscriptions

worldwide – roughly 87 percent of the world

population.2 Of those 6 billion mobile subscrip-

tions, 4.5 billion came from the developing

world, with adoption in China and India driving

much of the growth. Unsurprisingly, the top

three mobile operators in the world are from

these two countries (China Mobile, China

Unicom, and Bharti Airtel India, according to

Portio Research3).

In countries like this, which have large and

highly populated urban areas, there is a high-

level of telecommunications infrastructure

already in place in major cities. While extending

this infrastructure to rural areas with terrestrial

technology can be complicated and costly, sat-

ellite presents a strong complementary solution

that can overcome geographic barriers and

extend mobile network from cities to remote

areas affordably and efficiently.

ConclusionAs wireless communications technology contin-

ues to evolve and operators are able to offer

greater and more sophisticated high-speed

wireless data services to customers, they need

a solution that can backhaul data efficiently and

affordably. Because satellite can reach places

that no terrestrial technology can, it is the ideal

solution for mobile operators to reach remote

and rural areas that are lacking 3G and 4G cov-

erage. Additionally, as satellite technology con-

tinues to evolve with the development of band-

width management breakthroughs and integra-

tion with small cell technology, it is becoming

easier to deploy and significantly more afford-

able to manage.

By using satellite to extend cellular coverage to

remote and rural areas in Asia-Pacific, where

mobile technology continues to be the primary

way that individuals access the Internet, mobile

operators are able to expand their customer

base while also facilitating important economic

and social change by improving access to infor-

mation.

Richard Deasington has more than 25 years of experience in the telecommunications industry, holding senior level positions in

R&D and Engineering working closely on voice, data and transmission network systems. In his current role as Director of Market

Development for iDirect, Richard is currently responsible for leading iDirect’s engineering and sales efforts for GSM backhaul solutions.

Prior to joining iDirect, Richard held Managing Consultant position at PA Consulting Group and later Questus Ltd where he focused on

mobile systems: GSM and 3G systems in particular. He has been involved in a large range of mobile related activities from architecting

the world’s first shared 3G network to leading the design of a range of network planning tools. Richard has written several well-known

books and published many articles on subjects ranging from 3G power amplifier efficiency to network sharing and push-to-talk. Richard

holds a Bachelor of Science degree with Honors in Computer Science with Biology from the University of London.

1 http://www.itu.int/ITU-D/ict/facts/ 2011/material/ICTFactsFigures2011.pdf

2 http://www.itu.int/ITU-D/ict/statis-tics/at_glance/KeyTelecom.html

3 http://www.portioresearch.com/Ranking09.html